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LMG1210: Dead time cannot be adjusted.

Part Number: LMG1210

Tool/software:

Hi team,

Circuit diagram and waveforms are attached.
The first waveform is the one with the dead time adjusted to the minimum.
The second waveform shows the maximum dead time.
Even if we move only the falling edge of the high-side FAT, the rising edge of the low-side FET will also follow.
Are there any possible causes or countermeasures?
I have tried the following with no change.
(1) Change snubber circuit constants (10Ω and 470pF are added for noise suppression)
(2) Add gate resistor
(3) Add pull-down on the gate line
(4) Bootstrap capacitor constant change
(5) Add a capacitor in the gate line (to delay the rise of the low-side FET)
(6)Strengthen GND (ground connection)

Best Regards,
Ryu.

  • Hi Ryu,

    Due to US national holiday, please expect a delay in response.

    Our experts will be back in office next week.

    Thank you for your patience!

    Regards,

    Hiroki

  • Hello Ryu,

    The HO output is referenced to the HS voltage. On the scope capture, HO is being measured referenced ground and not HS. This is why the falling edge of HO appears to follow the rising edge of LO. HS is not pulled to ground until the low side FET turns on. HO-HS voltage can be measured with a differential probe.

    The circled dip on the max deadtime scope capture is HO turning off before LO turns on. Once LO turns on, HS is pulled to ground. 

    The dead time adjustment appears to be working correctly.

    Thanks,

    Walter